Methods for treatment and disposal of regulated medical waste

ABSTRACT

A method for safely treating and disposing of infectious biomedical waste and other hazardous materials is disclosed. The method involves alkaline hydrolysis of infectious agents contained in regulated medical waste or hazardous waste solutions. The infectious waste is immersed into a highly basic solvent which is then heated. The material containing the infectious agents is allowed to remain within the heated solvent until the hydrolyzable matter is fully digested, thereby forming a sterile solution and sterile solid waste. The sterile solution and solid waste may then be disposed of through standard means, such as in a sanitary sewage system or local landfill facility. The method also provides for the treatment of lipid soluble hazardous material contained in the regulated medical waste.

TECHNICAL FIELD

[0001] The present invention relates to the field of waste disposal.More particularly, the invention relates to methods for safely treatingand disposing of infectious biomedical waste and other hazardousmaterials.

BACKGROUND OF THE INVENTION

[0002] Today hospitals and other health-care organizations produceconsiderable amounts of infectious waste. This type of waste includessurgical gowns, surgical gloves, needles, instruments, glass, culturedishes, and other disposable matter exposed to blood and other bodyfluids of patients. Such waste is classified as “regulated medicalwaste” under federal regulations, disposal of which must comply withstrict governmental regulations.

[0003] Recently, Health-care organizations as well as RegulatoryAgencies have been concerned with the adequacy of existing cleaning anddisposal methods. It has been discovered that some potentially harmfulcells, such as prokaryotes, or harmful proteins may survive standardautoclaving procedures. Thus, more effective sterilization techniqueshave been sought for treating solid infectious biomedical waste.

[0004] In addition, universities and other research facilities likewiseproduce a significant level of such waste. In conducting experiments incell lines, tissues or upon animals, it is common to introduce dyes,toxic chemicals or infectious agents into the test subject. Aftercompletion of the test and analysis, due to the introduction ofinfectious agents or hazardous materials, the remaining tissue or animalcarcass falls under the classification of regulated medical waste. Inaddition, animal waste, animal bedding, handling materials and othermatter exposed to animal body fluids or excretions may also need to betreated as infectious or hazardous waste, thus requiring disposal inaccordance with applicable governmental regulations.

[0005] In addition, it is common for health care organizations today toclean materials, instruments or surface areas exposed to infectiousagents, including zoonotic agents, with disinfectants such asformaldehyde or glutaraldehyde. Spent cleaning solution is consideredhazardous liquid waste and must be disposed of in compliance withgovernment regulations. The cost of disposing of such waste, on aninstitutional basis, can be quite costly. In addition, formaldehyde,glutaraldehyde, phenols and like materials are commonly used forembalming tissues and in fixation of infectious biological materials.Thus, these tissues and the fixative agents must likewise be disposed ofin compliance with government regulations.

[0006] Currently, the two methods commonly used in disposing of suchwaste are incineration and burial. Presently Federal law imposes strictregulations for incineration of hazardous waste and infectiousbiomedical waste. However, incineration may be further limited by stateand local agencies. For example, incineration of regulated medical wasteor other hazardous waste is not available at all in some jurisdictionssuch as the major metropolitan areas of New York City, San Francisco andChicago. Furthermore, the general process of incineration itself, evenwhen no hazardous materials or regulated medical wastes are involved, issubject to additional regulations, such as those requiring a directlicense from a state or local environmental agency. Additionally, futureincreases in the requirements for incinerator designs and function underclean air regulations put in doubt the continued availability ofincineration as a method of disposing such wastes.

[0007] Presently, the only real alternative to incineration isautoclaving the solid waste and then burying the waste material in alicensed waste disposal facility. Currently there are a limited numberof such sites in the United States. It is extremely costly to dispose ofinfectious medical waste by this method. Further, one will appreciatethat the cost is exceedingly high for waste that comprises matter which,but for the potential infectious agents, could be disposed of using lesscostly local disposal facilities. Due to the extremely high costassociated with land burial and the limitations on access to licensedland burial sites, the feasibility of land burial as a method ofdisposing of such waste remains an ever growing concern for research andhealth-care facilities.

[0008] The known methods of disposing of regulated wastes generated bymany universities, health-care and research facilities faces anuncertain future under the ever narrowing scope of environmental laws.Furthermore each is extremely costly, putting an unneeded drain on thealready strained resources of universities, health-care organizationsand research facilities. Thus, a need exists for methods for disposingof infectious bio-medical wastes and other hazardous materials which issafe, environmentally friendly and less expensive than existing disposalmeans.

SUMMARY OF INVENTION

[0009] The aforesaid needs are satisfied and the limitations of theprior art overcome, in accordance with the principles of the presentinvention, by providing a method for producing safely disposablecompositions from regulated medical waste. This method comprises thesteps of providing a highly basic solvent, immersing the regulatedmedical waste within the highly basic solvent and heating the highlybasic solvent. Degradation of the regulated medical waste may beincreased by treating the waste under pressures above one atmosphere.The tissue or other matter potentially containing the infectious medicalwaste is allowed to remain within the highly basic solvent until thehydrolyzable matter is fully digested, thereby forming a sterilesolution and sterile solid waste. The aqueous solution and any solidwaste may then be disposed of through standard means, such as a sanitarysewage system and local landfill facilities. However, it will beappreciated that the amount of solid waste to be disposed of issubstantially reduced by the present invention.

[0010] In another aspect, hazardous materials may be removed from thedigest and separately disposed in an appropriate manner, such as alandfill designated for such hazardous wastes or a specially licensedhigh temperature furnace. Paraffin or wax may be added to the regulatedmedical waste prior to or after digestion. Upon heating of the materialsthe paraffin or wax melts and becomes distributed throughout the aqueoussolution. After the waste has been fully digested and the aqueoussolution is allowed to cool, the lipid-like materials separate out fromand float to the surface of the aqueous phase where they resolidify uponcooling to room temperature. Lipid soluble waste materials may then beremoved from the aqueous phase upon separation of the lipid phasebecause they have become incorporated within the lipid phase. Thus,removing the lipid phase from the solution effectively also removeslipid soluble hazardous materials not degraded or otherwise consumed inthe alkaline treatment.

[0011] Accordingly, it is a principle object of this invention toprovide a method for safely disposing of tissue and other mattercontaining infectious medical and/or other hazardous materials. Oneadvantage of this invention is that it allows for safe disposal of theregulated medical waste at significantly less expense to the research orhealth-care facility without harming or increasing the risk of harm tothe environment. An additional advantage of this invention is that themethod may be utilized without geographic limitations, satisfyingexisting governmental regulations at the federal, state and local level.Another advantage of this invention is that it preserves the evershrinking area available in the land burial sites.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 shows a partial cut-away elevated view of an apparatus forpracticing the present invention.

[0013]FIG. 2 shows a view of a screen mesh permeable container.

[0014]FIG. 3 shows an elevated view of a solid permeable container.

[0015]FIG. 4 shows a partial cut-away elevated view of an apparatus forpracticing the present invention utilizing a plurality of tanks.

[0016]FIG. 5 shows a schematic drawing of an apparatus for practicingthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0017] This invention involves a method for safely treating anddisposing of matter containing infectious medical and/or hazardous wastematerials and is designed and intended to comply with all Federal, stateand local laws or regulations applicable to disposal of such wastes. Inone aspect the method comprises the steps of immersing regulated medicalwaste within a highly basic solvent. The highly basic solvent is heated,and the tissue or other matter containing regulated medical andhazardous waste material is allowed to remain within the highly basicsolvent until fully digested, thereby forming a sterile partiallyneutralized aqueous solution and sterile solid waste free of infectiousagents, such as zoonotic agents or other hazardous materials. As usedherein, “infectious agents” refers to bacteria or organisms capable ofcausing infection in humans or animals including, but not limited to,zoonotic agents and prokaryotes. “Sterile” and “sterilzed” mean beingfree of infectious agents.

[0018] In addition, as used herein, the term “regulated medical waste”means any waste potentially containing infectious agents that can causeinfection in humans or animals. Such regulated medical waste mayinclude, but are not limited to tissue, cloth, plastic, paper, animalcarcasses, bedding and other matter potentially containing infectiousagents.

[0019] When the researcher is ready to dispose of the regulated medicalwaste, the waste is completely immersed in a highly basic solvent.Preferably, this solvent should have a pH of 13 to 14 and it may becomprised of a mixture of water and an alkali metal hydroxide oralkaline earth-metal hydroxide. An aqueous solution of NaOH and/or KOHis preferred. An example of such a suitable highly basic solvent mayconsist of a 0.1 molar to 2.5 molar solution of NaOH in water, orapproximately 0.4%-10% sodium hydroxide (by weight) in water. It hasbeen discovered that gelation of the digest upon flushing with coldwater may be avoided by using a highly basic solvent of 1.5 M NaOH ormore. In addition, in order to assure degradation of all infectiouswastes, including prokaryotes, the highly basic solvent should be heatedto a temperature of at least 110° C. and preferably 115°-180° C.

[0020] The waste should be immersed in enough highly basic solvent suchthat all tissue, cells, and cell components are completely digested;namely, hydrolyzing tissue proteins by breaking many of the peptidebonds and saponifying cell and tissue lipids. As used herein,“hydrolyzable material” refers to tissue, cells or cell components thatcontain proteins or lipids capable of undergoing hydrolysis orsaponification in the highly basic solvent. To ensure complete digestionof the hydrolyzable material, excess base is preferably used. One ratioassuring excess base to carry out the digestion of the waste tocompletion is a 1:10 ratio of sodium hydroxide to wet tissue weight. Afurther expression of this ratio is 40 Kg of NaOH in 500L H₂O added to500 kilograms tissue by weight. These ratios are given only asinstruction as how to conduct the method stated herein and not to limitthe nature of the invention; one using the method described herein mayfind ratios more economical and exact as the invention is practiced. Itwill be appreciated that lower ratios of alkali to waste may be used asthe degree of non-organic matter, such as glass and plastic, increases.

[0021] After immersing the regulated medical waste within the highlybasic solvent, it is most preferable to allow the reaction to proceed ina closed reaction vessel. Reducing the amount of CO₂ available to thereaction is beneficial in order to maintain the ideal rate andstoichiometry of the reaction. This may be done by simply removing orlimiting any contact that the highly basic solvent has with theenvironment. If the reaction is occurring within a tank, placing asuitable cover on top of the tank would suffice.

[0022] If the reaction between the regulated medical waste and highlybasic solvent were allowed to proceed at its natural rate, it may takean impractical amount of time. Conducting the reaction in a sealedvessel under increased pressure and temperature reduces the reactiontime needed to completely digest the tissue, cells and cell components.Increasing pressures above one atmosphere may be used in this regard,preferably from one to ten atmospheres. Furthermore, detergents at aconcentration of up to 1% by weight, examples being sodium laurylsulfate or deoxycholate, may be added to the highly basic solvent. Itshould also be noted that, if no lipid soluble hazardous wastes are tobe recovered, the addition of detergents also has the advantage ofdispersing non-saponifiable lipids, and aiding in the sterilization ofbiological materials.

[0023] In addition, shredding the solid waste prior to immersion withinthe highly basic solvent reduces the reaction time by making moresurface area accessible to the highly basic solvent. Still anothermethod capable of reducing the reaction time is provided by supplying anexcess of fresh highly basic solvent continuously onto the surface ofthe solid waste. This may be accomplished by agitating, circulating orstirring the solvent.

[0024] The reaction rate will ultimately depend on specific variablessuch as: the temperature of the solvent, pressure in the reactionvessels, nature of the waste and ratio of hydrolyzable material to thevolume of the highly basic solvent. As the reaction rate will vary, thetime that the waste must remain immersed in the highly basic solventwill also vary. However, regardless of the reaction rate, the wasteshould remain immersed within the highly basic solvent until thehydrolyzable matter is fully digested. Leaving the waste within theheated highly basic solution until complete digestion is achievedassures production of a sterile solution. Using excess base at 110°-180°C. and 1-10 atm, digestion will, in almost all instances, be completeafter 16-18 hours.

[0025] Once the animal tissue has been completely digested, two types ofsolid debris often remain. As used herein, the term “sterile solidwaste” includes the following two types of solid debris. The first typeof debris consists of metal, rubber or plastic, such as surgical clips,sutures, glass, and other pieces of plastic or paper. Solid items suchas these do not incorporate infectious medical waste and are completelysterilized after treatment. Thus, the treated solids may safely bedisposed as ordinary sterile solid waste after being isolated from thesolution and washed. The second type of solid debris remainingundissolved includes inorganic portions of the animal's skeletalstructure. After treatment, all organic components of the skeletalstructure are digested, leaving sterile calcium phosphate. The skeletalremains, when removed from the highly basic solvent and washed, areextremely friable and may be easily crushed. In fact, the skeletalremains are so friable that they may be crushed to form a disposablepowder by such relatively simple means, such as manual application ofpressure.

[0026] After the waste has been fully digested within the highly basicsolvent and the solid debris removed, the remaining “sterile solution”will comprise a sterile mixture of alkali metal salts of amino acids,sugar acids, nucleotides, small peptides, fatty acids from lipids,phosphates from lipids and nucleic acid breakdown, soluble calciumsalts, pigments, sugars, sugar alcohols, hydrocarbons and inorganicacids derived from the electrolytes normally found within tissue fluids.However, due to the heated alkaline treatment, infectious agents,including zoonotic agents and prokaryotes, are broken down into lowmolecular weight residues. Thus, it is entirely safe to dispose of thetreated solution and solids using disposal means such as septic tanks,sewage systems, local landfills and other disposal means appropriate forthe disposal of these simple non-hazardous materials.

[0027] Because the sterile solution at the end of the reaction processcontains only non-toxic biodegradable materials, dilution of thesolution may not be required for disposal. However, reducing thealkalinity the solution may be accomplished by diluting the solution,such as by adding excess water to the reaction vessel before it isdischarged or as it is being discharged. With the majority ofapplications the resulting solution is well within the level ofalkalinity that is safely disposable as sanitary sewage. Dilution mayalso be accomplished by one skilled in the art by calculation of thedilution of the specific unit of waste volume by the entire waste volumeof the institution or manufacturing plant.

[0028] As indicated above, it is common to clean instruments and surfaceareas exposed to infectious agents with formaldehyde, glutaraldehyde andlike agents. In addition, formaldehyde, glutaraldehyde, phenols and likematerials are commonly used as fixating agents for biological tissues.Spent cleaning solution and fixatives are considered hazardous materialswhich must be disposed of in accord with applicable governmentalregulations. As used herein, the term “hazardous waste solution” refersto spent cleaning solution or fixative, as described above.

[0029] It has been discovered that spent cleaning solutions containinghazardous materials, such as formaldehyde or glutaraldehyde, may besafely disposed of together with the digestion of regulated medicalwastes. Up to 30 gallons of formaldehyde or glutaraldehyde, typically a2-4% solution by weight, may be degraded in conjunction with 250 lbs. oftissue. Hazardous materials such as formaldehyde, glutaraldehyde,phenols, and other materials react in the above alkaline treatment toform harmless non-toxic materials. For example, when formaldehyde andphenol are in solution under the alkaline conditions a harmless inertplastic like material is formed. Also, the aldehydes by themselves reactirreversibly with the tissue amino groups to form harmless products.Thus, the term “sterile solid waste” also includes the aforementionedplastic like material and harmless products.

[0030] However, not all hazardous materials will break down into inertby-products under the temperature and conditions described above. Thus,when the regulated medical waste material incorporates hazardousmaterials capable of withstanding the above conditions, additional stepsmust be undertaken to ensure degradation or extraction of the hazardousmaterials within the resulting solution. Lipid soluble hazardousmaterials such as halogenated aliphatic and aromatic hydrocarbons, PCBs,chlorinated insecticides, many dyes and materials of like solubility maybe extracted from the aqueous digest based on their solubility inlipids. Paraffin or wax, preferably in solid form, may be added to thewaste material to be digested. Upon heating, the added materials meltand, with the aid of the soaps formed during alkaline saponification offatty tissue, the materials become finely dispersed throughout thedigest. After digestion is completed, typically after sixteen toeighteen hours, the mixture is allowed to cool to room temperature(about 20° to 25° C.), preferably without stirring. The lipid phaseseparates from the aqueous phase upon cooling and due to the solubilitycharacteristics of the hazardous material, the lipid phase incorporatesthe lipid-soluble hazardous waste. The solid lipid phase floating on thetop of the aqueous phase may then be easily removed from the digest,such as by straining. Thus, this method avoids the difficult and costlyprocedures associated with most liquid-liquid extractions. Theresolidified solid lipid material, such as a paraffin cake, may then bedisposed of accordingly. For example, where the solid lipid containstoxic or highly regulated materials, such as PCBs, the solid lipidextract may be disposed in the appropriate hazardous waste facility.This extraction process may be repeated, if necessary, for lipid-solublecompounds with partial solubility in the aqueous phase to allow forquantitative extraction of such compounds.

[0031] In this regard it is important to note that the volume of thehazardous material, and hence the cost in properly disposing of thesame, has been considerably reduced since the large constituent ofharmless biodegradable organic mater, such as peptides, sugars and aminoacids have been separated from the toxic substance. Suitable paraffinsand waxes include, but are not limited to ordinary household paraffins,carnauba wax, bees wax, mixtures of alkanes, and mixtures ofhydrocarbons, long chain fatty acids, esters and alcohols that aresolids at room temperature. In the event the hazardous material isinsoluble in lipids, other known liquid-liquid extraction methods may beemployed, the specific application of which will vary with regard to theparticular hazardous material.

[0032] Disposal of the regulated medical waste should be prompt becausethe organic material begins to decompose immediately under roomtemperatures. Thus, the regulated waste must be dealt with soon after itis produced in order to avoid the creation of noxious odors and otherhealth hazards. However, freezing of the regulated medical wasteeffectively prevents decomposition and the creation of noxious odors andhealth hazards. Thus, when it is not economical or practically feasibleto dispose of the waste on a daily basis, the regulated medical wastemay be frozen and stored in that condition until an appropriate time oramount of waste for disposal is acquired. Temporary storage of the wasteby freezing may be accomplished by any refrigeration means capable ofmaintaining a temperature of 0° Celsius or below and capable of storingthe amount of waste desired.

[0033] An apparatus for producing a safely disposable solution fromregulated medical waste can be seen in reference to FIGS. 1-5, such anapparatus comprises the following elements: a sealable tank 10 with ahighly basic solvent 12 therein, a permeable container 22 for storingregulated medical waste, a water supply means 28, a filtering means 20,a pressurizing and venting means 15 and a disposal means 32.

[0034] A preferred apparatus comprises a singular tank or vessel capableof containing a solution. The tank must be made of a material that iscapable of withstanding the pH levels, temperatures and pressuresutilized in this process, an example being stainless steel.

[0035] The reaction between the highly basic solvent 12 and theregulated medical waste, such as the tissue, cloth, paper or othermatter, takes place within a tank 10. However, it is preferable for thereaction to occur within a closed reaction vessel in order to preventCO₂ from the atmosphere from entering the reaction path. Thus, the tank10 preferably has a sealing means 14 capable of withstanding thechemicals, temperatures and pressures utilized in this process, anexample being stainless steel. When only one atmosphere of pressure isutilized, it is possible for the sealing means 14 to simply comprise afitted cover. However, when increased pressure is utilized, the sealingmeans 14 must be more complex, being pressure and air tight. This may beaccomplished through the use of an alkali resistant gasket and a coversealed to the tank with clamps 16. A pressurizing means 15 may be fittedto sealed tank 10 in order to increase the pressure therein.Furthermore, in an alternative embodiment the sealing means 14 may alsocontain a pressure gauge to monitor the reaction vessel, adjustablesafety valves, and a sampling port 17 for measurement of the pH of thereaction mixture. The sealing means 14 may further contain an internalwater supply means, such as a sprinkler, attached to a water supply viaa valved clock in order to automate the process.

[0036] As discussed above, the process requires that the highly basicsolution 12 be heated in order to assure degradation of all infectiousagents and proper sterilization of the solid matter. Therefore, aheating means 18 is necessary to heat the highly basic solvent 12. Anyheating means 18 commonly known and used today for heating solutionscould be utilized in this process. One example of such a heating means18 is a stainless steel heating jacket, in which heated water or steamcirculates between the walls of a double walled tank, thereby heatingthe solution within the tank. Alternatively, the tank 10 may be fittedwith an electric heating mantle, placed upon a hot pad, or fitted withan internal heating coil.

[0037] As discussed above, after the hydrolyzable waste has been fullydigested, there often remains undigested solid debris, i.e. skeletalremains, glass or plastic. Thus, the preferred embodiment contains afiltering means 20, as shown in FIG. 1., for removing the solid debrisbefore or during disposal of the sterile solution. An example of asuitable filter would be a 40 mesh/25.4 mm stainless steel screen. Thefiltering means 20 may be placed in combination with the removal means30 such that the sterile solution is filtered as it is removed from thetank 10.

[0038] The apparatus may also have a permeable container 22 capable ofholding the waste. The permeable container 22 may be utilized to immersethe waste within the highly basic solvent 12. This container may alsoact as the filtering means and/or a means for removing the solid sterileundigested debris. When the hydrolyzable matter is fully digested, thepermeable container 22 may be removed, thereby removing the undigestedsolid debris remaining within the permeable container 22. The containershould be made of a material capable of withstanding the pH levels,chemicals and temperatures involved in this process. In addition, thecontainer should be permeable to liquids, small peptides and aminoacids. An example of such a container can be seen in reference to FIG. 2and FIG. 3. A container having 3.2 to 6.4 mm stainless steel screen meshbasket may suffice in practicing the method disclosed herein, such ascan be seen in FIG. 2. When a large amount of waste is to be moved orheld, the screen mesh basket should be reinforced with stainless steelbands. Alternatively, as seen in FIG. 3, the container may comprise of asolid stainless steel container with 3.2 or 6.4 mm holes drilledtherein. These baskets may be shaped and sized to be removably fittedwithin of the above mentioned tank 10, with sufficient clearance toallow liquid to circulate over all surfaces of its contents. It is alsopossible that these containers could be sized such that they fit withinthe refrigeration means 40, as shown in FIG. 4, thereby reducing thework and components necessary to complete this process.

[0039] Because the natural reaction time is very slow, the preferredinvention may also contain an agitating means 24 to help speed up thereaction rate by keeping the solvent or the substrate in motion whilethe reaction is taking place. A means for agitating or simply moving thesolid undigested waste within the highly basic solvent 12 may accomplishits task by simply moving the permeable container 22 holding the animalremains. In addition, it is also possible to accomplish the same resultby circulating the highly basic solvent 12. This may be accomplished bya wide variety of means well known in the art today, examples beingmechanical stirrers or pumping means. However, any pump connected to thetank 10 via piping and valves must be capable of withstanding thetemperatures, chemicals and pressure involved.

[0040] An exhaustion or ventilation means 26 such as a ventilated hoodmay be placed over the tank 10 and be positively ventilated in order toremove any excess carbon dioxide or noxious fumes produced by performingthe method disclosed herein.

[0041] Depending on the size of the tanks 10 and the amount ofhydrolyzable waste being digested, it may be possible to dilute theresulting sterile solution, directly within the tank 10 before drainingsaid tank 10. However, not all tanks will be large enough to dilute themixture created by the reaction. In such a case, dilution may occursimultaneously with draining of the tank 10. In either case, it isnecessary to have a water supply means 28, preferably with a stop valve29. The appropriate amount of water may be added as the solution drainsor is pumped from the tank 10. This may be accomplished with any meansfor adding water, examples being any faucet, hose or lead connected to awater supply capable of delivering the rates necessary.

[0042] Finally, an apparatus for practicing the present invention maycontain a means for emptying the contents 30 of the tank 10. One maysimply use a drainage port and let gravity drain the solution from thetanks. Such a port would preferably be fitted with a removable screenfilter 20 to retain small non-hydrolyzable materials that may haveescaped from the basket during the digestion process. Alternatively,pumps may be used to drain the tanks of their contents. However, anypump utilized in this apparatus should be made of stainless steel withall seals and liners made of a material capable of withstanding strongalkaline action; an example being Teflon®. Materials such as glass,ceramics, rubber, and most synthetics should not be used due to theirvulnerability to alkaline actions. The piping and valves used in thecirculation of the solvent may be linked to or comprise the same pipingand valves utilized in the draining and flushing of the tank. Inaddition, if a pump is utilized to circulate the highly basic solvent 12this same pump may be utilized to drain the reaction mixture.

[0043] Preferred safety controls on any drainage system would includemeasurements of pH by port sampling or continuous flow analysis withinput of both sets of data going to a manually or electronicallycontrolled valving system. Specifically, manual or automated systemsmust receive information on the final pH of the solvent at thecompletion of the digestion process before dilution can be calculatedand implemented in order to initiate discharge of the vessel.

[0044] An alternative embodiment of an apparatus for practicing thepresent invention is shown in FIG. 4, comprising a plurality of tanks, ahighly basic solution 12 within the first tank 34, a less basic solution37 in the second tank 36, a neutral solution 39 in the third tank 38,and means for removing the solutions 30 therein. The first tank 34 mayhave additional modifications shown in FIG. 1, unlike the additionaltanks, such as a heating means 18, a sealing means 14, an agitatingmeans 24, and a pressurizing means 17. Since these modifications areonly necessary for the tank in which the reaction actually takes place,any additional tanks would not require these modifications. Furthercomprising the alternative apparatus in FIG. 4 are a refrigeration means40 for storage of the waste, a means for moving the permeable container42, a ventilation means 26, a water supply means 28 and a disposal means32.

[0045] As can be seen from FIG. 4, it is possible for the apparatus toutilize a plurality of tanks. The tanks may be located in proximity toone another such as in a linear or circular series. When a single tankis used, this tank will contain the highly basic solvent 12. However,when a plurality of tanks is used, the first tank 34 in the series maycontain a highly basic solvent 12 and the second tank 36 and subsequenttanks containing a less basic solution. Preferably the second tank 36contains a solution 37 having a pH of approximately 10. The solution ofthe second tank 36 may be comprised of one percent sodium hypochlorite;i.e., a 1:5 dilution of household chlorine bleach and water. The thirdtank 38 in the series may contain a solution 39 having a pH ofapproximately 7, such as water. The second and third tanks may beutilized to rinse off the highly basic solvent 12 that remains upon thepermeable container 22 and the solid non-hydrolyzable debris. This maybe accomplished by moving the permeable container 22 and/or solid debrissequentially through the tanks. Use of all three tanks is optional asuse of either 1, 2, 3 or more tanks is possible. When only two tanks areutilized, it is preferable for the second tank to contain a solutionhaving a pH of approximately 7, such as water.

[0046] It may also be necessary to provide a means for moving thecontainer 42 housing the waste therein. The means necessary to completethis function is highly dependent upon the amount of waste a intended tobe disposed. If it is to be done in small amounts and, therefore smallweights are involved, a less sophisticated or complex means could beused. Possible means range from simple winch and pulley systems to moremechanized apparatus such as forklifts, hydraulic apparatus, ormechanized winches. It may be advantageous that the moving means 42 besized such that it can move the containers from tank 34 to tank 36 witha hood 26 remaining in place over the tanks.

[0047] A further component of the apparatus may include a freezer 40. Asindicated above, it may be desirous to store the tissue or other mattercontaining infectious waste for a period of time before disposing of theanimal tissue a freezer when disposal is not conducted on a daily basis.

[0048] As can be seen in reference to FIG. 5, other embodiments capableof manual or automated operation may be designed without departing fromthe scope of the present invention. This particular embodiment disclosesa sealable tank 10 having a top lid 44, a water inlet port 46, an airvent 48 and pressure gauge 50. A steam jacket 52 surrounds the length ofthe tank 10 and has separate condensate outlet 54 and steam inlet 56on-off valves. Condensate outlet 54 may also be used as a cooling waterinlet to circulate cooling water into jacket 52, and steam inlet 56 maybe used to exit the cooling water from the jacket. A single pump 58 maybe used and is connected to the various drainage and sampling ports viaa system of connecting pipes and valves, such as the pump to vesselshut-off valve 60, the sampling valve 62, the pump to drainage shutoffvalve 64 and the lower pipe drainage and alkali inlet valve 68. Thebottom of tank 10 is also fitted with a temperature sensor 72. All ofwhich may be run manually or by an automating means, such as amicroprocessor connected to the various sensors, pumps and valves.

[0049] Although the invention has been described in the terms of thepreferred embodiments, it is apparent to those skilled in the art thatvarious modifications, substitutions, equivalents and other changes maybe utilized without departing from the spirit of the invention.

We claim:
 1. A method for treating regulated medical waste comprisingthe steps of: (a) providing a highly basic solvent; (b) immersing saidregulated medical waste into said highly basic solvent, wherein saidregulated medical waste contains infectious agents, and said infectiousagents comprise hydrolyzable material; and (c) heating said highly basicsolvent and said immersed regulated medical waste to a temperature andfor a time sufficient to digest said hydrolyzable material, whereby asterile solution comprising non-toxic biodegradable materials andcontaining sterile solid waste free of said infectious agents isproduced.
 2. The method of claim 1 , wherein said highly basic solventhas a pH in the range of about 13 to about
 14. 3. The method of claim 1, wherein said highly basic solvent comprises a mixture of water and analkali metal hydroxide or alkaline earth-metal hydroxide.
 4. The methodof claim 1 , wherein said heating step (c) is performed at a temperatureof at least 110° C.
 5. The method of claim 2 , wherein said temperatureis in the range of about 115° C. to about 180° C.
 6. The method of claim1 , wherein step (c) is performed at a pressure of at least oneatmosphere.
 7. The method of claim 6 , wherein said pressure is in therange of about one to ten atmospheres.
 8. The method of claim 1 ,wherein said highly basic solvent also includes a detergent at aconcentration of up to 1% by weight.
 9. The method of claim 1 furthercomprising in step (b) adding a hazardous waste solution into saidhighly basic solvent, wherein said hazardous waste solution alsocontains said infectious agents comprising hydrolyzable material. 10.The method of claim 9 , wherein said hazardous waste solution comprisesformaldehyde, glutaraldehyde, phenols, or mixtures thereof, andinfectious agents.
 11. The method of claim 1 , wherein said regulatedmedical waste further contains lipid soluble hazardous material, saidmethod further comprising between steps (b) and (c) the step of adding aparaffin or wax to said highly basic solvent containing said regulatedmedical waste, wherein upon heating in step (c) said lipid solublehazardous material and said paraffin or wax are dispersed throughoutsaid sterile solution.
 12. The method of claim 11 further comprisingafter step (c) a cooling step, wherein upon cooling to room temperature,said lipid soluble hazardous material and said paraffin or wax separatefrom said sterile solution to form a solid lipid phase atop said sterilesolution.
 13. The method of claim 12 further comprising removing saidsolid lipid phase.
 14. The method of claim 1 , wherein said regulatedmedical waste further contains lipid soluble hazardous material, saidmethod further comprising in step (c) adding a paraffin or wax to saidhighly basic solvent containing said regulated medical waste, whereinupon heating in step (c) said lipid soluble hazardous material and saidparaffin or wax are dispersed throughout said sterile solution.
 15. Themethod of claim 14 further comprising after step (c) a cooling step,wherein upon cooling to room temperature, said lipid soluble hazardousmaterial and said paraffin or wax separate from sterile solution to forma solid lipid phase atop said sterile solution.
 16. The method of claim15 further comprising removing said solid lipid phase.
 17. The method ofclaim 1 further comprising agitating, circulating, or stirring thehighly basic solvent in step (c).
 18. The method of claim 1 furthercomprising reducing the alkalinity of said sterile solution by dilutionwith water.
 19. The method of claim 1 further comprising disposing ofsaid sterile solution and said sterile solid waste.
 20. The method ofclaim 1 further comprising the step of removing said sterile solid wastefrom said sterile solution.
 21. A method for removing infectious agentsfrom a hazardous waste solution comprising the steps of: (a) providing ahighly basic solvent having a pH in the range of about 13 to about 14;(b) contacting said hazardous waste solution containing said infectiousagents and said highly basic solvent, wherein said infectious agentscomprise hydrolyzable material; and (c) heating said highly basicsolvent and said hazardous waste solution to a temperature and for atime sufficient to digest said hydrolyzable material, whereby a sterilesolution comprising non-toxic biodegradable materials and containingsterile solid waste free of said infectious agents is produced.
 22. Themethod of claim 21 , wherein said hazardous waste solution comprisesformaldehyde, glutaraldehyde, phenols, or mixtures thereof, andinfectious agents.
 23. A method for producing a sterile solution from ahazardous waste solution comprising the steps of: (a) providing a highlybasic solvent having a pH in the range of about 13 to about 14; (b)contacting said hazardous waste solution and said highly basic solvent,wherein said hazardous waste solution comprises hydrolyzable materialcomprising biological tissues, cells, or cell components, andformaldehyde, glutaraldehyde, phenols, or mixtures thereof; and (c)heating said highly basic solvent and said hazardous waste solution to atemperature and for a time sufficient to digest said hydrolyzablematerial, whereby a sterile solution comprising non-toxic biodegradablematerials and containing sterile solid waste is produced.